Yamazaki H, etal., J Atheroscler Thromb. 2019 Mar 1;26(3):246-259. doi: 10.5551/jat.44040. Epub 2018 Oct 4.
AIM: Acyl-CoA cholesterol acyltransferase 1 (ACAT1) esterifies free cholesterol to cholesteryl esters (CE), which are subsequently hydrolyzed by neutral cholesterol ester hydrolase 1 (NCEH1). The elimination of ACAT1
an> in vitro reduces the amounts of CE accumulated in Nceh1-deficient macrophages. The present study aimed at examining whether the loss of ACAT1 attenuates atherosclerosis which is aggravated by the loss of NCEH1 in vivo. METHODS: Low density lipoprotein receptor (Ldlr)-deficient mice were transplanted with bone marrow from wild-type mice and mice lacking ACAT1, NCEH1, or both. The four types of mice were fed a high-cholesterol diet and, then, were examined for atherosclerosis. RESULTS: The cross-sectional lesion size of the recipients of Nceh1-deficient bone marrow was 1.6-fold larger than that of the wild-type bone marrow. The lesions of the recipients of Nceh1-deficient bone marrow were enriched with MOMA2-positive macrophages compared with the lesions of the recipients of the wild-type bone marrow. The size and the macrophage content of the lesions of the recipients of bone marrow lacking both ACAT1 and NCEH1 were significantly smaller than the recipients of the Nceh1-deficient bone marrow, indicating that the loss of ACAT1 decreases the excess CE in the Nceh1-deficient lesions. The collagen-rich and/or mucin-rich areas and en face lesion size were enlarged in the recipients of the Acat1－/－ bone marrow compared with those of the recipients of the WT bone marrow. CONCLUSION: The loss of ACAT1 in bone marrow-derived cells attenuates atherosclerosis, which is aggravated by the loss of NCEH1, corroborating the in vitro functions of ACAT1 (formation of CE) and NCEH1 (hydrolysis of CE).
Wen P, etal., Zhonghua Yi Xue Yi Chuan Xue Za Zhi. 2016 Jun;33(3):286-91. doi: 10.3760/cma.j.issn.1003-9406.2016.03.002.
OBJECTIVE: To investigate the clinical phenotype and ACAT1 gene mutation in a family affected with beta-ketothiolase deficiency (BKTD). METHODS: Clinical features and laboratory test data were collected. The probands were monozygotic twin brothers. Genomic DNA w
as isolated from peripheral blood leukocytes obtained from the probands and their family members. Molecular genetic testing of the ACAT1 gene was carried out. RESULTS: The probands have presented with fever, vomiting and severe ketoacidosis. By arterial blood gas testing, pH was determined to be 7.164, bicarbonate was 4.0 mmol/L, and urine ketone was ++++. Urinary organic acid gas chromatography-mass spectrometry analysis showed excessive excretion of 3-hydroxybutyric acid, 2-methyl-3-hydroxybutyric acid and tiglylglycine. Increased 3-hydroxybutyrylcarnitine (C4-OH), tiglylcarnitine(C5:1) and 3-hydroxyisovalerylcarnitine (C5-OH) levels. The clinical phenotype of proband's parents were both normal, but an elder sister turned out to be an affected patient. Genetic analysis has identified two heterozygous mutations [c.622C>T(p.R208X) and c.653C>T (p.S218F)] in the proband, which were respectively detected in the mother and father. The c.653C>T (p.S218F) mutation was not found among the 100 healthy controls and has not been included in the Human Gene Mutation Database(HGMD). CONCLUSION: The primary clinical manifestations of BKTD is ketoacidosis. Urine organic acid and blood acylcarnitine analyses play an important role in the diagnosis of the disease. The compound heterozygous of ACAT1 gene mutations probably underlie the BKTD in our patient.
Objective- ACAT1 (Acyl-CoA cholesterol acyltransferase 1) esterifies cellular free cholesterol, thereby converting macrophages to cholesteryl ester-laden foam cells in atherosclerotic lesions and cutaneous xanthoma. Paradoxically, however, loss of ACAT1
ont-weight:700;'>ACAT1 in bone marrow causes the aggravation of atherosclerosis and the development of severe cutaneous xanthoma in hyperlipidemic mice. Recently, it has been reported that cholesterol crystals activate NLRP3 (NACHT, LRR [leucine-rich repeats], and PYD [pyrin domain] domain-containing protein 3) inflammasomes, thereby contributing to the development of atherosclerosis. The present study aimed to clarify the role of NLRP3 inflammasomes in the worsening of atherosclerosis and cutaneous xanthoma induced by ACAT1 deficiency. Approach and Results- Ldlr-null mice were transplanted with bone marrow from WT (wild type) mice and mice lacking ACAT1, NLRP3, or both. After the 4 types of mice were fed high-cholesterol diets, we compared their atherosclerosis and skin lesions. The mice transplanted with Acat1-null bone marrow developed severe cutaneous xanthoma, which was filled with numerous macrophages and cholesterol clefts and had markedly increased expression of inflammatory cytokines, and increased atherosclerosis. Loss of NLRP3 completely reversed the cutaneous xanthoma, whereas it improved the atherosclerosis only partially. Acat1-null peritoneal macrophages showed enhanced expression of CHOP (C/EBP [CCAAT/enhancer binding protein] homologous protein) and TNF-α (tumor necrosis factor-α) but no evidence of inflammasome activation, after treatment with acetylated LDL (low-density lipoprotein). Conclusions- Elimination of ACAT1 in bone marrow-derived cells aggravates cutaneous xanthoma and atherosclerosis. The development of cutaneous xanthoma is induced mainly via the NLRP3 inflammasome activation.
Lo YW, etal., J Cell Mol Med. 2015 Apr;19(4):744-59. doi: 10.1111/jcmm.12388. Epub 2015 Jan 30.
Mitochondria are key organelles in mammary cells in responsible for a number of cellular functions including cell survival and energy metabolism. Moreover, mitochondria are one of the major targets under doxorubicin treatment. In this study, low-abundant mitochondrial proteins were enriched for prot
eomic analysis with the state-of-the-art two-dimensional differential gel electrophoresis (2D-DIGE) and matrix-assistant laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) strategy to compare and identify the mitochondrial protein profiling changes in response to the development of doxorubicin resistance in human uterine cancer cells. The mitochondrial proteomic results demonstrate more than fifteen hundred protein features were resolved from the equal amount pooled of three purified mitochondrial proteins and 101 differentially expressed spots were identified. In which, 39 out of these 101 identified proteins belong to mitochondrial proteins. Mitochondrial proteins such as acetyl-CoA acetyltransferase (ACAT1) and malate dehydrogenase (MDH2) have not been reported with the roles on the formation of doxorubicin resistance in our knowledge. Further studies have used RNA interference and cell viability analysis to evidence the essential roles of ACAT1 and MDH2 on their potency in the formation of doxorubicin resistance through increased cell viability and decreased cell apoptosis during doxorubicin treatment. To sum up, our current mitochondrial proteomic approaches allowed us to identify numerous proteins, including ACAT1 and MDH2, involved in various drug-resistance-forming mechanisms. Our results provide potential diagnostic markers and therapeutic candidates for the treatment of doxorubicin-resistant uterine cancer.
Cholesterol esters are a key ingredient of foamy cells in atherosclerotic lesions; their formation is catalyzed by two enzymes: acyl-CoA:cholesterol acyltransferases (ACATs; also called sterol O-acyltransferases, or SOATs) ACAT1 and ACAT2. ACAT1
ht:700;'>ACAT1 is present in all body cells and is the major isoenzyme in macrophages. Whether blocking ACAT1 benefits atherosclerosis has been under debate for more than a decade. Previously, our laboratory developed a myeloid-specific Acat1 knockout (KO) mouse (Acat1-M/-M), devoid of ACAT1 only in macrophages, microglia, and neutrophils. In previous work using the ApoE KO (ApoE-/-) mouse model for early lesions, Acat1-M/-M significantly reduced lesion macrophage content and suppressed atherosclerosis progression. In advanced lesions, cholesterol crystals become a prominent feature. Here we evaluated the effects of Acat1-M/-M in the ApoE KO mouse model for more advanced lesions and found that mice lacking myeloid Acat1 had significantly reduced lesion cholesterol crystal contents. Acat1-M/-M also significantly reduced lesion size and macrophage content without increasing apoptotic cell death. Cell culture studies showed that inhibiting ACAT1 in macrophages caused cells to produce less proinflammatory responses upon cholesterol loading by acetyl low-density lipoprotein. In advanced lesions, Acat1-M/-M reduced but did not eliminate foamy cells. In advanced plaques isolated from ApoE-/- mice, immunostainings showed that both ACAT1 and ACAT2 are present. In cell culture, both enzymes are present in macrophages and smooth muscle cells and contribute to cholesterol ester biosynthesis. Overall, our results support the notion that targeting ACAT1 or targeting both ACAT1 and ACAT2 in macrophages is a novel strategy to treat advanced lesions.
